Projection gun

ABSTRACT

An improved projection gun for products in the form of particles, said gun being of light construction and permitting projections of product at relatively-high flow-rates. The gun comprises a plurality of tubes fixed between a rear end-plate and a projection nozzle, said tubes serving to receive an intake tube for the projected product and a high-tension cable for electrically charging the product, the interstitial space between the tubes and an external sleeve being used to form a conduit for auxiliary air which passes into a distribution chamber and thence through tangential passages, so as to give a whirling motion to the projected products. This gun may be employed for the projection of powder, paint, varnish, enamel, etc...

United States Paten [151 3,682,384 Sulsse [451 Aug. 8, 1972 PROJECTION GUN I [72] Inventor: Georges Suisse, Echirolles, France 'f Henson wood Assistant Exammer-Thomas C. Culp, Jr. Filed? l l 22, Attomey-Lee C. Robinson, Jr. [21] Appl. No.: 30,794

. [57] ABSTRACT 30 Fomign Application priority Data Atn irangrtlived pisijectiogi gun goducts in the forr:

o p c es, sai gun eing o 1 t construction an April22,1969 France ..69lll65 permitting projections of product at relatively high flow-rates. The gun comprises a plurality of tubes 8i. ..239/15, 239/3, fixed Petween a rear endmlate and a projection nob Field 139 417 5 zle, said tubes serving to receive an intake tube for the pzrfijectil productth and a high-tension cable for electric y c arging e product, the interstitial space [56] References cued between the tubes and anexternal sleeve being used UNITED PATENTS so forgn a conguit in auiglifhry air which passes into a istri ution 0 am r an ence through tangential 2/ llovey etal ..239/417.5 passages, so as to give a whirling motion to the prol 641,58l 41927 E2228 jected Products. This may employed for the 3,351,285 11/1967 Tholome ..239/15 projection powder palm vamlsh enamel 3,086,711 4/1963 Point ..239/l5 5 Claims, 2 Drawing Figures 1317205 1623 wqgl i qssaszan 2? 53A :!3 I saw 25 o ,a at s l s? 35 :"IIZIM!I w MI R\ PROJECTION GUN The present invention relates to a projection gun for products in particle form, and in particular to an electrostatic gun of the kind comprising a conduit for conveying the said product, when so required a conduit for a high-tension cable, and a conduit for a flow of auxiliary air ensuring a whirling movement of the particles at the outlet of a projection nozzle, the said conduits extending from the level of a gripping handle along a portion forming the barrel of the gun, towards the said projection nozzle.

In the majority of the known devices, there is utilized a solid insulating member forming the barrel, along which are formed passages for the product to be projected, the air to be conveyed and the high-tension cable.

This type of construction is heavy, and it has already been proposed to form the structure of the gun barrel by an assembly of insulating tubes forming conduits which are held between end-plates, thereby permitting the formation of interstitial spaces between the tubes, thus ensuring a lighter form of construction. However, in order to obtain greater rigidity of this tubular mounting, it is generally necessary to enclose the assembly of the tubes by a sleeve forming a casing which ensures a correct performance of the assembly.

The present invention has for its object improvements in this type of gun which are intended to improve its lightness still further.

According to a characteristic feature of the invention, the insulating tubes which are fixed between the end-plates are employed solely for conveying the product to be projected, and when so required for receiving the high-tension cable, while the interstitial space between the said tubes and the reinforcing sleeve serves itself to convey the auxiliary air ensuring the whirling motion of the projected product. In this way, one of the tubes is eliminated without interfering in any way with the transfer of this auxiliary air which has a conduit section in the interstitial space between the tubes amply sufficient to ensure its conveyance to the spraying nozzle.

The characteristic features and advantages of the invention will furthermore be brought out in the description which follows below by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a view in longitudinal section of a gun according to the invention;

FIG. 2 is a view in transverse section taken along the line ll-ll of FIG. 1.

Referring to the accompanying drawings, a gun for the projection of powder comprises a handle 1 supporting an upper portion 2 forming a barrel. This portion 2 which fomrs the barrel is constituted by two tubes 3 and 4 which are fixed at their rear extremity in sockets 5, 6 of a rear end-plate 7, and at the front extremity they pass into perforations 8, 9 in a transverse wall 10 which extends towards the front in a cylindrical form 1 l.

The tube 3 serves as a housing for a conduit 12 for the product to be projected, for example air which conveys the powder, while the tube 4 serves as a housing for a high-tension cable 13 terminating in a pin 14 passing into an end piece in the form of a socket member 15. The socket member 15 is affixed to a cylindrical resistance element 40 housed in the front portion of the tube 4 and penetrating considerably into the internal space formed by the cylindrical wall 11.

The assembly is rigidly held in an outer sleeve 16 which is fixed by screwing into the inside of a rear collar 17 supported against the end plate 7, and at the front extremity into the interior of a cylindrical portion 18 which extends the wall 11 of the nozzle chamber towards the rear. Fluid-tight sealing points are provided at the rear at 19 and 20.

At the level of the nozzle, the conduit 12 for the air which conveys the powder communicates with the interior of a member 21 forming a hub for supporting the nozzle, this member 21 being provided for that purpose with a clearance 22 on the one hand and a radial endportion 23 on the other. The clearance portion 22 serves as a housing for a tubular portion 24 carrying a deflecting wall 26 which forms an ionizing electrode at its peripheral edge, while the end-plate portion 23 carries the insulating external wall 25 of the nozzle, of frusto conical shape, provided with a radial end-plate 27 supported against the edge of the wall 11 against which it is applied in a fluid-tight manner by a collar 28.

The high-tension cable 13 is connected electrically to the resistance element 40 which is itself in contact in the interior of the, nozzle by a spring 29 with the metal hub 21 and from thence through the intermediary of the tubular portion 24, to the electric discharge electrode 26. The interstitial space between the sleeve 16 and the tubes 3 and 4 communicates by a perforation 31 with the interior of the nozzle chamber 32 and from thence through the conduits 33 and 34 with an interstitial space 35 between the outer nozzle body 25 and the tubular portion 24.

These passages 33 and 34 are preferably four, six or more in number and are inclined in the direction perpendicular to the plane of the drawing so as to pass tangentially into the interstitial space 35, contrary to what has been shown in the drawing, in which, for the sake of clearness, radial communications only have been shown between the distribution chamber 32 and the interstitial space 35. On the upstream side, the interstitial space between the tubes 3 and 4 on the one hand and the sleeve 16 on the other, communicates by a perforation 36 with an auxiliary air inlet tube 37, while a trigger head 38 controls a switch 39 to permit the intake of powder, high-tension supply, and secondary air to the gun.

It can be seen that the construction which has just been described permits, as compared with previous constructions, the elimination of at least one of the conduits while providing the same advantages for the conveyance of the auxiliary air. In this way, greater lightness is obtained and the handling of the gun is facilitated.

The invention is not limited to a gun for projecting powder, but it can of course also be applied to guns for spraying liquid particles, such as paint, enamel, varnish, etc... ln view of the increased lightness which is obtained by means of the arrangement according to the invention, this form of construction is particularly suitable for guns intended to deliver high flow-rates of sprayed particles or powder.

I claim:

1. ln portable projection apparatus for discharging and applying an electrostatic charge to a product to be projected, the combination comprising:

hand-held barrel means defining an internal conduit; projection nozzle means carried adjacent one end of the barrel means and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said chamber defining means forming an annular chamber disposed around the discharge portion and at least one passage which extends from the chamber into the space between the chamber defining means and the discharge portion, said chamber communicating with said internal conduit; plurality of longitudinally extending conduits eccentrically disposed within the internal conduit to form an interstitial space between: the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected at one end to the projection nozzle means;

' means for supplying project to be projected to one of the longitudinally extending conduits, said one conduit communicating with the discharge portion of said projection nozzle means to discharge the product therefrom;

means for applying a high dc. voltage to the other longitudinally extending conduit, said other conduit being in electrically conductive relationship with the projection nozzle means to apply an electrostatic charge to the product; and

means for directing fluid to the internal conduit and long said interstitial space to said chamber, said fluid being discharged through said passage to provide an auxiliary fluid flow adjacent the discharged product.

2. In portable projection apparatus as defined in claim 1, said other longitudinally extending conduit comprising:

an electrical conductor protruding through the end of the barrel means opposite that adjacent the projection nozzle means, and

a resistance element connected to said conductor within the barrel means.

3. in portable projection apparatus for discharging and applying an electrostatic charge to a product to be projected, the combinationcomprising:

barrel means defining a internal conduit;

a handle having a control trigger affixed to the barrel means;

projection nozzle means carried adjacent one end of the barrel means and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said .chamber defining means forming an annular chamber disposed around the discharge portion and a plurality of passages which extend tangentially from the chamber into the space between the chamber defining means and the discharge portion, said chamber communicating with said internal conduit;

a plurality of longitudinally extending conduits ec- I centrically disposed within the internal conduit to form an interstitial space between the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected at one end to the projection nozzle means;

means for supplying product to be projected to one of the longitudinally extending conduits, said one c ndu communicatin with the disc ar e rti n 0 said pro ection nozle means to illsc ial ge e product therefrom;

means for applying a high dc. voltage to the other longitudinally extending conduit, said other conduit being in electrically conductive relationship with the projection nozzle means to apply an electrostatic charge to the product; and

means for directing fluid through said handle and ing:

barrel means defining an internal conduit; projection nozzle means carried adjacent one end of the barrel means and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said chamber defining means forming an annular chamber disposed around the discharge portion and at least one passage which extends from the chamber into the space between the chamber defining means and the discharge portion, said passage extending in a direction tangent to said annular chamber and said chamber communicating with said internal conduit;

plurality of longitudinally extending conduits eccentrically disposed within the internal conduit, to form an interstitial space between the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected to the projection nozzle means;

means for supplying product to be projected to one means for directing fluid to the internal conduit and along said interstitial space to said chamber, said fluid being discharged through said passage to pro vide an auxiliary fluid flow adjacent the discharged product.

5. ln portable projection apparatus as defined in claim 4,

means defining a transverse wall at the end of the barrel means opposite that adjacent the projection nozzle means, said longitudinally extending conduits protruding through said transverse wall. 

1. In portable projection apparatus for discharging and applying an electrostatic charge to a product to be projected, the combination comprising: hand-held barrel means defining an internal conduit; projection nozzle means carried adjacent one end of the barrel mEans and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said chamber defining means forming an annular chamber disposed around the discharge portion and at least one passage which extends from the chamber into the space between the chamber defining means and the discharge portion, said chamber communicating with said internal conduit; a plurality of longitudinally extending conduits eccentrically disposed within the internal conduit to form an interstitial space between the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected at one end to the projection nozzle means; means for supplying project to be projected to one of the longitudinally extending conduits, said one conduit communicating with the discharge portion of said projection nozzle means to discharge the product therefrom; means for applying a high d.c. voltage to the other longitudinally extending conduit, said other conduit being in electrically conductive relationship with the projection nozzle means to apply an electrostatic charge to the product; and means for directing fluid to the internal conduit and long said interstitial space to said chamber, said fluid being discharged through said passage to provide an auxiliary fluid flow adjacent the discharged product.
 2. In portable projection apparatus as defined in claim 1, said other longitudinally extending conduit comprising: an electrical conductor protruding through the end of the barrel means opposite that adjacent the projection nozzle means, and a resistance element connected to said conductor within the barrel means.
 3. In portable projection apparatus for discharging and applying an electrostatic charge to a product to be projected, the combination comprising: barrel means defining a internal conduit; a handle having a control trigger affixed to the barrel means; projection nozzle means carried adjacent one end of the barrel means and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said chamber defining means forming an annular chamber disposed around the discharge portion and a plurality of passages which extend tangentially from the chamber into the space between the chamber defining means and the discharge portion, said chamber communicating with said internal conduit; a plurality of longitudinally extending conduits eccentrically disposed within the internal conduit to form an interstitial space between the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected at one end to the projection nozzle means; means for supplying product to be projected to one of the longitudinally extending conduits, said one conduit communicating with the discharge portion of said projection nozzle means to discharge the product therefrom; means for applying a high d.c. voltage to the other longitudinally extending conduit, said other conduit being in electrically conductive relationship with the projection nozzle means to apply an electrostatic charge to the product; and means for directing fluid through said handle and into the internal conduit, said fluid flowing along said interstitial space to said chamber and being discharged through said passages to provide an auxiliary fluid flow adjacent the discharged product.
 4. In projection apparatus, the combination comprising: barrel means defining an internal conduit; projection nozzle means carried adjacent one end of the barrel means and including a discharge portion and chamber defining means in spaced relationship with the discharge portion, said chamber defining means forming an annular chamber disposed around the discharge portion and at least one passage which extends from the chamber into the space between the chamber defining means and the discharge portion, said passage extending in a direction tangeNt to said annular chamber and said chamber communicating with said internal conduit; a plurality of longitudinally extending conduits eccentrically disposed within the internal conduit, to form an interstitial space between the longitudinal conduits and the barrel means, each of said longitudinally extending conduits being connected to the projection nozzle means; means for supplying product to be projected to one of the longitudinally extending conduits, said one conduit communicating with the discharge portion of said projection nozzle means to discharge the product therefrom; and means for directing fluid to the internal conduit and along said interstitial space to said chamber, said fluid being discharged through said passage to provide an auxiliary fluid flow adjacent the discharged product.
 5. In portable projection apparatus as defined in claim 4, means defining a transverse wall at the end of the barrel means opposite that adjacent the projection nozzle means, said longitudinally extending conduits protruding through said transverse wall. 